Final Diagnosis -- Ganglioglioma with Neurofibrillary Tangles

Postoperatively, the patient followed an unremarkable course with no significant headaches or neurologic deficits. He has also been free of seizures and returned to work with no difficulty.

Gangliogliomas are rare benign neoplasms comprised of glial and neuronal components. The incidence is greatest among children and young adults representing only 0.4% to 1.3% of CNS tumors (1). Most commonly, gangliogliomas will present clinically with seizures resistant to pharmacotherapy and less often with focal neurologic signs or increased intracranial pressure (1).

On MRI, these tumors can appear cystic, solid, or cystic and solid with calcifications appreciated on CT. Eighty four percent of gangliogliomas occur in the temporal lobes, 10% in the frontal lobes, 2% in the occipital lobes, and 4% are infratentorial (1).

To this day, it is not clear what cells give rise to this neoplasm. Some suggest that it is primitive cells that differentiate into the glial and neuronal lines while others support the idea that the glial and neuronal components are actively dividing (2).

Another mystery is the presence of neurofibrillary tangles (NFTs) in the neoplastic ganglion cells. This phenomenon has been reported four other times with this case being the fifth (3, 4, 5, 6).

NFTs, normally associated with Alzheimer's disease but present in a large series of diseases of infectious, malformative, metabolic, traumatic, and neurodegenerative nature, are composed of microtubule associated protein tau (MAP-tau). Hyperphosphorylated tau combines with normally phosphorylated tau to form thin filaments within the cytoplasm of the neuron. When glycosylated, the filaments become paired into a structure known as a paired helical filament (PHF). (7)

It is not clear if the abundant NFTs identified within the neuronal component of this and previously reported cases (3,4,5,6) are a primary feature of the tumor produced by genetic or metabolic abnormalities of the neoplastic neurons or a secondary degenerative process. Molecular and genetic studies of the neuronal component have to be done to clarify this issue.